Department of Public Health entomologist Linn Haramis tells The Pantagraph that the state had about 40 confirmed cases in 2000. By 2010, the number increased to 200 confirmed cases. The provisional total for 2016 is nearly 350 cases.

"Ticks carry a shockingly large number of illnesses," said Steven Juliano, an Illinois State University distinguished professor of ecology.

Illinois State University assistant professor of infectious disease ecology Ben Sadd said one reason for the uptick in such illnesses could be global warming. He said fewer ticks, and the small mammals they feed on, die during milder winters.

"Conditions are favorable to ticks and their hosts (such as mice) when it's warm and wet," Sadd said. "Climate change could accelerate tick development, which could impact tick-borne illnesses."

Juliano advises anyone who thinks they may have encountered a tick-borne illness to get tested, evaluated and treated by a doctor. He said the earlier a case is treated, the better the outcome.

"Ticks are nasty critters, but they aren't a reason to be scared of the woods," said Dr. Kirsten Pieper, a central Illinois veterinarian. "Use common sense and enjoy nature."